A conventional fire distinguishing device detects smoke, heat, or flames or the like, and based on factors such as the concentration of smoke detected, distinguishes the presence or absence of fire. For example, a fire sensor has been proposed having a smoke detection section which detects a smoke signal which varies according to the concentration of smoke, an external temperature detection section which detects and outputs the external temperature of the sensor, and an internal temperature detection section which detects and outputs the internal temperature of the sensor. This fire sensor detects the external temperature, the internal temperature, and the temperature difference between the external temperature and the internal temperature when exposed to the heat of a fire, and decides a predetermined correction factor based on the detected external temperature and the temperature difference. Furthermore, this fire sensor, by multiplying the decided correction factor with the smoke signal detected by the smoke detection section to correct the smoke detection characteristics, achieves the early detection of fires and prevents false alarms (refer to Patent Document 1, for example).
In fire sensors such as that described above, to detect a fire at an early stage and issue an alarm is of foremost importance. However, suppressing false alarms when no fire exists is also important. Thus, as a feature to prevent false alarms when no fire exists, an accumulation feature has been used. This accumulation feature is a feature which, when for some reason the smoke concentration or the like reaches a constant reference value at which a fire outbreak is considered to have occurred, judges that an actual fire has occurred and issues an alarm only if the reference value continues to be maintained after a predetermined cumulative time has elapsed. Fire receivers exist which use this accumulation feature to detect fires at an early stage and reduce false alarms (refer to Patent Document 2, for example).    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2000-137875    Patent Document 2: Japanese Unexamined Patent Application, First Publication No. 2004-265148